Process for parboiling rice

Abstract

This invention relates to a process for parboiling rough rice, which process includes: (1) soaking the rough rice; (2) subjecting the soaked rough rice to a first value of microwave energy to partially gelatinize the starch in the rice and raise its water content; (3) draining free water, if any, from the treated soaked rough rice; and (4) subjecting the drained rough rice from (3) to a second level of microwave energy to effect substantially complete gelatinization and to lower the rough rice water content.

We claim: 
     
       1. A process for producing parboiled rice, which process comprises: (a) soaking rough rice in water at a temperature of from about 40° C. to about 70° C. until said rough rice has a water content within the range of from about 26 wt. % to about 32 wt. %;   (b) treating a slurry of free water and the soaked rough rice from (a) with a first value of microwave energy to partially gelatinize the starch in the endosperm portion of said rough rice and to raise the water content of said rough rice to be within the range of from about 32 wt. % to about 40 wt. %;   (c) draining substantially all of the free water, if any, from the treated slurry of free water and rough rice from (b);   (d) treating the drained rough rice from (c) with a second value of microwave energy to substantially complete said gelatinization of said starch and to reduce the water content of the thus treated rough rice to about 22 wt. %; and   (e) drying the rough rice from (d) to reduce its water content to at least 14 wt. %.   
     
     
       2. The process of claim 1 wherein said soaking in (a) is for a period of time within the range of from about 3.5 hours to about 5 hours. 
     
     
       3. The process of claim 1 wherein the temperature of the slurry of free water and rough rice in (b) is raised to be within the range of from about 95° C. to about 100° C. during said treatment in (b). 
     
     
       4. The process of claim 1 wherein the higheht temperature of the drained rough rice in (d) is within the range of from about 90° C. to about 110° C. during said treatment in (d). 
     
     
       5. The process of claim 1 wherein said drying in (e) is effected by passing hot air over the treated rough rice from (d). 
     
     
       6. The process of claim 2 wherein the temperature of the slurry of free water and rough rice in (b) is raised to be within the range of from about 95° C. to about 100° C. during said treatment in (b). 
     
     
       7. The process of claim 6 wherein the highest temperature of the drained rough rice in (d) is within the range of from about 90° C. to about 110° C. during said treatment in (d). 
     
     
       8. The process of claim 7 wherein said drying in (e) is effected by passing hot air over the treated rough rice from (d).